1. Field of the Invention
The invention relates to a micromechanical sensor element.
A chemical reaction can easily be characterized or detected at the interface with a solid body. Therefore, a chemical reaction of this type is often used in chemical and pharmaceutical analysis. Analysis methods of this type are suitable both for large series of tests in pharmaceutical research and for what are known as home-care applications.
2. Description of the Related Prior Art
“J. Wang, Towards Genoelectronics: Electrochemical Biosensing of DNA-Hybridization, Chem. Eur. J., Vol. 5, No. 6, 1999, gives an overview of various methods used to detect chemical bonds at an interface with a solid body.”
The various methods used to detect chemical bonds at an interface of a solid body can be substantially divided into four classes of method, namely into optical, electrical, chemical and mass spectroscopy methods.
However, hitherto the analysis of chemical surface reactions has according to every known method been carried out using relatively expensive macroscopic or optical methods, and the evaluation of the data determined by means of discrete electronics.
“Furthermore, Gunther, Use of oscillating crystals for weighing thin films and for micro-weighing, Zeitschrift fur Physik 155, pp. 206-222, 1999, has disclosed what is known as the EACM method (Electrochemical Quartz-Crystal Microbalance method), which also makes use of the fact that the electrically stimulatable resonant frequency of an oscillating crystal which is coated with a metal on two sides has a defined dependency on the interface condition of the metal electrodes (mass change of the oscillating mass) and on their environment (for example the viscosity of a liquid). If a chemical reaction is carried out at the surface of a quartz crystal which has been coated in this manner, the resonant frequency of the system under consideration changes.”
“Furthermore, T. Abe et al, One-chip multichannel quarts crystal microbalance (QCM) fabricated by Deep RIE, Sensors and Actuators, No. 82, pp. 139-143, 2000 and WO 89/09938 to Charych, et al., have described QCM arrangements (Quartz-Crystal Microbalance arrangements) and coupling layers for these arrangements.”
“W. K. Schubert et al., Chemical Sensing with a magnetically-excited flexural plate wave resonator, Electrochemical Society Proceedings, Vol. 99-23, pp. 332-335, 1999 describes an FPW resonator (Flexural Plate Wave resonator) which is used as a sensor element. In the case of the FPW resonator, the deflection of a membrane and the detection of the frequency change are carried out using electromagnetic means.”
“E. A. Wachter et al., Micromechanical sensors for chemical and physical measurements, Rev. Sci. Instrum. 66(6), pp. 3662-3667, June 1995 describes a cantilever as an oscillatable element, with the frequency being detected by optical means.”